I'm sure that this will all make more sense to me once I download and try BookCreator and Calibre, but I am still confused as to whether I need to create margins for MOBI (and other eBook formats), like I do for print files. Can you give me some guidance regarding that? Also, do I need to make the page a certain size, or is that all done through BookCreator/Calibre?

Thanks again!

1. Either no margins or absolute minimum margins. The outer frame/body of the ereader device serves for visual margin. The text should fill as much of the device's display as possible. Most format conversions will ignore the margins in an original file if that file is not a true ebook format.

2. Ebooks don't have pages and shouldn't force any page-like structure. Text is flowed at the discretion of the reader device. This makes the original document's page size a non-issue.

Everyone has the personal favorite set of tools. I currently use Calibre to create ebooks from non-ebook formats (e.g. RTF, HTML, ...). I usually generate an ePub format ebook in Calibre as a first step. I then use Sigil, a free ePub editor, to tweak the book formatting before using Calibre to convert the ePub into the desired final format, which for me is a MOBI file for my K3.